Make sal/config.h the first in pch

By convention, it should be the first include in C/CXX files;
so use of pch should not break that.

Change-Id: Ic329c5f39e8f48ad1778724368e262e48972342b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/112123
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

cppcanvas/inc/pch/precompiled_cppcanvas.hxx

@@ -13,13 +13,14 @@
  manual changes will be rewritten by the next run of update_pch.sh (which presumably
  also fixes all possible problems, so it's usually better to use it).
 
- Generated on 2021-03-06 20:41:34 using:
+ Generated on 2021-03-08 13:12:52 using:
  ./bin/update_pch cppcanvas cppcanvas --cutoff=11 --exclude:system --include:module --include:local
 
  If after updating build fails, use the following command to locate conflicting headers:
  ./bin/update_pch_bisect ./cppcanvas/inc/pch/precompiled_cppcanvas.hxx "make cppcanvas.build" --find-conflicts
 */
 
+#include <sal/config.h>
 #if PCH_LEVEL >= 1
 #include <algorithm>
 #include <cassert>
@@ -65,7 +66,6 @@
 #include <rtl/textenc.h>
 #include <rtl/ustring.h>
 #include <rtl/ustring.hxx>
-#include <sal/config.h>
 #include <sal/log.hxx>
 #include <sal/macros.h>
 #include <sal/saldllapi.h>